Telephone-exchange



(No Model.) 3 Sheets--Sheet 1.

M. BROOKS. I TELEPHONE EXCHANGE.

No. 533,785. Patented Feb. 5, 1895.

a l Ilxllllll'l IR l ur (No Model.) 3 Sheets-Sheet 2.

M. BROOKS.

TELEPHONE EXCHANGE.

N0. 533.785. Patented Feb. 5, 1895.

s .ru 8 Du h S m e ,e h S 3 H G u S Km 0X OE R BM D M L E T (No Model.)

No. 533,785. Patented Feb. 5, 1895.

Jeff

flmyanfirooks. jy w UNITED STATES PATENT OFFICE.

MORGAN BROOKS, OF MINNEAPOLIS, MINNESOTA.

TELEPHONE-EXCHANGE.

Q'PEGIFICATION forming part of Letters Patent No. 533,785, datedFebruary 5, 1895. Application filed October 17,1894. Serial No. 526,188.(No model.)

To aZZ whom it may concern.-

Be it known that I, MORGAN Baoons, of Minneapolis, in the county ofHennepin and State of Minnesota, have invented a certain new andImproved Telephone-Exchange, of which the followin is a specification.

My invention relates to telephone exchange methods and systems and hasfor its object the provision of means whereby the lines of distantsubscribers may be connected without actual metallic contact, thereby atonce simplifying exchange apparatus and avoiding the annoying featuresof the present metallic contact systems. A further and more particularobject of the invention is to provide means for connecting severaldifferent lines or circuits by induction, and a further object is tocheapen the construction of central station apparatus and lessen boththe cost of operation and main tenance thereof.

To these ends myinvention consists in the method of and apparatus forconnecting two or more electric circuits or more particularly telephonecircuits, all as hereinafter described and particularly pointed out inthe claims.

My invention will be more readily understood by reference to theaccompanying drawings, forming a part of this specification, and inwhich- Figure 1 is ageneral perspective view showing a switch-boardprovided with apparatus embodying my invention. Fig. 2 is an enlargedsectional view of one of the induction connectors or pair of terminals.Fig. 3 is a diagrammatic View illustrating my method and system. Fig. 4is asimilar diagrammatic view of one of the induction bridges or loops.Fig. 5 is a sectional view illustrating a modified form of theelectrical terminals or switches. Fig. 6is adiagrammatical viewillustrating the use of condensers asinduction terminals.

The invention may be best understood by reference to Fig. 3, wherein A,B, O, D, E, F, G, H, I represent nine subscribers telephone outfits inthe circuit 4 of each of which a simple coil 2 of wire is included, allof the coils being upon the switch board in the central station. Asshown in Fig. 2 the wire making up these coils is wound upon suitableshells 5 and as shown in Fig. 1 these several termi nals or permanentcoils are closely arranged upon a suitable board or table 10. Anannunciator ll of any desired form may be included in the centralstation end of each subscribers line. The permanent coils are adapted toreceive other independent and movable coils or plugs which arepreferably arranged in pairs 6 and 7 joined by conductors incased insuitable cords 8. These plugcoils are preferably wound upon an iron core12 and both the plug-coils and the permanent coils are preferablytapered, as shown in Fig. 2, to facilitate the introduction of the oneinto the other.

The subscribers outfit may be of any desired form, say the ordinary set,as shown at A, wherein the battery transmitting circuit is strictlylocal. The telephone operators set may be similar, comprising thereceiver 13, transmitter 14, battery 15 and induction coil 16.

17 represent permanent coils included in the circuit of the telephoneoperators set and one of these coils is preferably provided for eachpair of loop-plugs, one of the plugs of each loop or bridge normallyresting in an operators permanent coil. A subscriber wishing aconnection with another line operates the magneto in his set, and, thereceiver being on the hook, sends current over the line and reieases thedrop 11 whereupon the operator places one of the loop plugs in thepermanent coil belonging to the calling subscriber, while the other plugremains in the operators permanent coil 17. The subscriber, taking thereceiver from the hook, completes the circuit through the receiver andtransmitter cutting out the magneto and bell and bringing the batteryinto use, thereby energizing the coil 2 included in the line, which,through its field of force induces a current in the plug-coil within thesame, the plug-coil becoming the secondary of a completed inductioncoil. The subscriber may then talk over the line, energy beingtransmitted through the coil 7 and thus through the other plug-coil,which, becoming the primary coil in the secondary or permanent coilwithin the operators circuit, transmits current or energy thereto forthe operation of the receiver. The

operator may talk back over the line by virtue of battery in thetransmitter circuit andthus inquire the number of the subscriber calledfor. Obtaining the same the plug 6 will be withdrawn from the operatorspermanent coil and placed .in the permanent coil 2 belonging to thesubscriber with whom connection is desired by subscriber A, after whichthese subscribers may talk as freely and satisfactorily as if connectedin direct circuit, current or electrical energy being induced from onecircuit to another through the induction bridges formed by the connectedplugcoils.

In some cases I prefer to dispense with the use of the induction bridge,or connecting circuit, and employ permanent coils, any two of which uponthe switch-board may be placed together or within respective fields,electrical energy being induced from one to the other directly. Devicesadapted for this use are shown in Fig. 5, where separable parts whenplaced together form a closed-magnetic-circuit induction-coil. Thedevices are similar to that shown in Fig. 2 except that the coils aredoubled or duplicated and are rendered interchangeable by thearrangement of both the inner coil 18 and an outer coil 19 upon eachU-section or yoke 20 of the iron ring or link. The wire is wound uponsuitable spools or shells supported upon the iron parts 20, which partsare extended to form the cores of the smaller coils and are providedwith the taper heads 21 which fit snugly into the recesses 22 providedin the butts of the opposite yoke-pieces, the two pieces of iron in eachcase making a firm contact to render the magnetic circuit as complete aspossible. The two coils upon each yoke-piece or U 20 may be connected inseries with one another and in the circuit of the telephone and when thedouble coils are brought together it is obvious that current or energyin one pair will induce current in the other and in its circuit. It isobvious that these double coils may be substituted for the singlepermanent coils 2 and loop-cords provided with similar terminalsemployed in connection therewith. The principal advantage, however, liesin their interchangeability, which enables the two similar parts, whenmounted with cords, to be placed togetherthereby avoiding the secondrepetition otherwise made in the bridge.

I have not thought it necessary to illustrate means whereby the operatormay ring up the several subscribers as many calling systems may beemployed equally well with my apparatus.

It is obvious that other forms of induction terminals may be used and toillustrate this I have shown,in Fig. 6, condensers employed in placethereof, and further to show that my system is perfectly flexible asregards the use of grounded or metallic circuits, I have shown a diagramof grounded circuits. The subscribers circuit 25 terminates in ground atthe instrument and in a condenser 26 at the central station and includesan annunciator 27 on the switch-board. Loop-plugs are preferablyemployed each end of the loop 28 scares being provided with a condenserplate 29, which being inserted between the plates belonging to differentsubscribers circuits connect such circuits through induction. Theoperator is here again provided with a permanent terminal 30 in the formof a condenser wherein one of the plug condenser plates may be inserted,for the purpose of conversing with the calling subscriber. By means ofkey-controlled connections with the loops or bridges current may be sentfrom an alternating current machine 31 to ring the bells of thesubscribers sets.

One of the principal advantages which I claim for my system is that itpermits of the adjustment of each induction terminal to the peculiarconditions of the circuit in which it is included. Thus, for instance, asubscribers line or a trunk line, longer than others would be given moreturns of wire in its permanent coil, while a shorter line would havefewer turns. Thus each circuit would be arranged always to the bestadvantage. I believe that the same advantage may be acquired in the useof the condensers by the comparison and adjustment of relative surfacesin the condensers belonging to the different circuits. For the purposeof listening in by the operator it maybe found desirable to provide anadditional induction connector in each pair of coils. It is obvious thatby thus connecting the different circuits by means of induction, all ofthe many annoyances of actual metallic contact systems are avoided.Further it is obvious that there are many equivalents for the severalportions of my apparatus and which would really suggest themselves toone skilled in the art and I therefore do not confine my invention tothe specific constructions and arrangements herein specified.

Having thus described and ascertained the nature of my said inventionand the manner in which it is to be performed, I claim as new and desireto secure by Letters Patent- 1. The combination, in a telephone system,of a subscribcrs circuit, with a permanent coil included therein, amovable second subscribers circuit, and a second coil connectedtherewith and adapted to be placed within the field of said permanentcoil whereby electrical energy is induced upon the second line orcircuit, substantially as described.

2. The combination, in a telephone system, of two subscribers circuits,with induction terminals in said circuits respectively, and a bridgecircuit including movable induction terminals to be placed in proximityto or within the fields of force of the first mentioned terminals,whereby an lnductional connection is completed between said subscriberscircuits, substantially as described.

3. The combination, in a telephone system, of a number of subscriberscircuits, with a primary induction terminal included in each of saidcircuits at the central station, a source of electricity included ineach of said lines,

IIO

and a movable secondary induction terminal at the central station,whereby two of said primary terminals may be inductively connected,substantially as described.

4. The combination, in a telephone system, of a number of subscriberscircuits,and permanent coils included in said circuits respectively,said permanent coils being arranged in proximity to one another, asource of electricity included in each of said circuits,

and plug-coils included in short circuits, said plug-coils adapted to beinserted or arranged respectively in proximity to any two of saidpermanent coils, as and for the purpose specified.

5. The combination, in a telephone system, of a series of subscriberscircuits, with induction terminals included in the same respectively,movable means for connecting said subscribers circuits by induction, anoperators circuit and movable inductional means for connecting the samewith either of said subscribers circuits, substantially as described.

6. The combination, in a telephone system, of a series of subscriberscircuits, with induction terminals included in said circuitsrespectively, a bridge circuit including independent and movableinduction terminals adapted to be placed in the fields of the firstmentioned terminals, a telephone operators set, and means whereby thesubscribers instruments are connected therewith, substantially asdescribed.

7. The combination, in a telephone system, of a series of subscriberscircuits, each including a movable induction terminal, with an operatorscircuit, also including such a movable terminal whereby said circuitsmay be connected with one another or with the operators circuit,substantially as described.

8. The induction terminals or connectors comprising each a hollow coiland an iron core coil together mounted upon an iron yoke, the twoterminals being adapted to be placed together to form aclosed magneticcircuit induction coil, substantially as described.

9. The combination, in atelephone system, of a series of subscriberscircuits, with means for connecting the same, each of said subscriberscircuits including an induction coil or terminal, an operators telephoneset, the circuit thereof, and a movable induction coil or terminalincluded therein and adapted to be placed within the field of asubscribers induction terminal, whereby talking or signaling circuitsare established.

10. Fhe combination, in a telephone system, of a subscribers circuit,with a primary induction terminal included therein, a second subscriberscircuit, and a secondary induction terminal operatively connected withthe second subscribers circuit, said terminal being movable to the endthat the same may be placed within the field of said primary terminal toinductively connect said subscribers circuits, substantially asdescribed.

In testimony whereof I have hereunto set my hand this 9th day ofOctober, A. D. 189st.

MORGAN BROOKS.

In presence of- O. G. HAWLEY, F. S. LYON.

Correction in Letters Patent No. 533,785

It is hereby certified that in Letters Patent No. 533,785, grantedFebruary 5, 1895, upon the application of Morgan Brooks, of Minneapolis,Minnesota, for an improvement in Telephone Exchanges, an error appearsin the printed specification requiring correction, as follows: In line115, page 2, the Word movable should be stricken out and inserted beforethe Word second in line 116 same page and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Ofiice.

Signed, countersigned, and sealed this 19th day of March, A. D. 1895.

[sEAL] JNO. M. REYNOLDS,

Assistant Secretary of the Interior.

Countersigned:

J OHN S. SEYMOUR,

Commissioner of Patents.

It is hereby certified that in Letters Patent No. 533,785, grantedFebruary 5, 1895,

for an improveupon the application of Morgan Brooks, of Minneapolis,Minnesota,

ment in Telephone Exchanges, an error appears in the printedspecification requiring correction, as follows: In line 115, page 2, theWord movable should be stricken out and inserted before the Word secondin line 116 same page and that the said Letters Patent should be readwith this correction therein that the same may conform to the record ofthe case in the Patent Office.

Signed, countersigned, and sealed this 19th day of March, A. D. 1895.

[snub] JNO. M. REYNOLDS,

Assistant Secretory 0f the Interior.

Countersigned:

JOHN S. SEYMOUR,

Cmmnissioner of Patents.

